Hotpatching

game_re/CMakeLists.txt

@@ -96,6 +96,7 @@ function(setup_target TARGET DBG_MODE)
       COMMAND ${gh_tool} -d${CMAKE_CURRENT_SOURCE_DIR}/gh.db
         hooks -o ${CMAKE_CURRENT_BINARY_DIR}/hooks.def
     )
+    target_include_directories(${TARGET} PRIVATE ${CMAKE_CURRENT_BINARY_DIR})
 
     target_sources(${TARGET} PRIVATE
       ${CMAKE_CURRENT_BINARY_DIR}/hooks.def

game_re/r3/binders/dbg_mem.cxx

@@ -3,14 +3,21 @@
 #include <windows.h>
 #include <DbgHelp.h>
 #include <memoryapi.h>
+#include <hooker.h>
 
 #define GH_BASE_ADDR 0x00400000
 
 static uintptr_t g_gh_translationOffset{};
 
+extern "C" {
+#define HOOK(addr, name) void name(void *);
+#include "hooks.def"
+#undef HOOK
+}
+
 struct R3Bin {
   R3Bin() { loadOriginal(); }
- 
+
   void loadOriginal() {
     SPDLOG_DEBUG("Loading original binary");
 
@@ -27,12 +34,15 @@ struct R3Bin {
         uintptr_t(module) - GH_BASE_ADDR;
 
     // Now we have to relocate the module to the new base address
-    relocateModule(module);
+    relocateModule();
+    patchFunctions();
   }
 
-  inline void relocate(HMODULE module, void* instr, void* from, void* originalPointee) {
-    void* relocated_addr = (void*)(uintptr_t(from) + translationOffset);
-    void* relocated_to = (void*)(uintptr_t(originalPointee) + translationOffset);
+  inline void relocate(void *instr, void *from,
+                       void *originalPointee) {
+    void *relocated_addr = (void *)(uintptr_t(from) + translationOffset);
+    void *relocated_to =
+        (void *)(uintptr_t(originalPointee) + translationOffset);
     void *checkRead{};
     SIZE_T numRead{};
     ReadProcessMemory(GetCurrentProcess(), relocated_addr, &checkRead,
@@ -40,12 +50,14 @@ struct R3Bin {
     if (numRead != 4 || checkRead != originalPointee) {
       throw std::logic_error("Invalid relocation");
     }
-    WriteProcessMemory(GetCurrentProcess(), relocated_addr, &relocated_to, sizeof(relocated_to), NULL);
+    WriteProcessMemory(GetCurrentProcess(), relocated_addr, &relocated_to,
+                       sizeof(relocated_to), NULL);
   }
-  
-  void relocateModule(HMODULE module) {
-    #define REL(instr, from, originalPointee) relocate(module, (void*)(instr), (void*)(from), (void*)(originalPointee));
-    #include "relocations.def"
+
+  void relocateModule() {
+#define REL(instr, from, originalPointee)                                      \
+  relocate((void *)(instr), (void *)(from), (void *)(originalPointee));
+#include "relocations.def"
   }
 
   // Translate address relative from the original image base address
@@ -148,6 +160,19 @@ struct R3Bin {
     }
   }
 
+  // Fixes up the target address (RVA) to jump into the patched function
+  void patchFunction(void *at, void *new_addr, const char *name) {
+    SPDLOG_DEBUG("Patching function {} at {}", name, at);
+    void *resolved = translateAddress(at);
+    if (!hooker_write_jmp(resolved, new_addr))
+      throw std::runtime_error(fmt::format(
+          "Failed to patch function {} at {} (RVA: {})", name, resolved, at));
+  }
+  void patchFunctions() {
+#define HOOK(addr, name) patchFunction((void*)addr, &name, #name);
+#include "hooks.def"
+  }
+
   HINSTANCE module;
   uintptr_t translationOffset;